1. Technical Field
The disclosed embodiments relate to a DC-AC converter and conversion circuit.
2. Description of the Related Art
In a conventional low-frequency isolated DC-AC converter, an output voltage of a post-stage AC inverter delivers the AC power required by a load through a transformer. A conventional low-frequency output transformer for such low-frequency isolated DC-AC converter is large in volume and has its output power limited by the output transformer.
In a conventional high-frequency isolated DC-AC converter, a DC-DC converter is generally implemented as a pre-stage circuit for controlling the DC link voltage, and energy is transmitted via a transformer to a secondary side through high-frequency switching. In the conventional high-frequency isolated DC-AC converter, a capacitor is connected in parallel of the secondary side for filtering and energy storage. An AC inverter as a post-stage circuit of the conventional high-frequency isolated DC-AC converter controls the output voltage and frequency. As the conventional high-frequency isolated DC-AC converter operates based on high-frequency switching, and loss resulted by the switching gets larger as the switching frequency increases, circuit conversion efficiency is degraded.
In a conventional isolated DC-AC converter, an output capacitor of a DC link as an energy buffer for post-stage AC inverter. Hence, as the output power increases, not only the size of the output capacitor of the DC link gets larger but also the circuit volume and cost are increased. Although a large-capacitance electrolyte capacitor is generally used as filtering component, the electrolyte capacitor yet suffers from a relatively shorter lifespan than other circuit components. Therefore, it is necessary for preventing the utilization of an electrolyte capacitor from as a component in a DC-AC converter to increase an overall operating lifespan of the DC-AC converter.